Answer:
The speed of the rock when it is at height h/4 is 
.
Explanation:
At maximum height the final velocity of the rock is equal to 0. Let u is the initial velocity of the rock. Using the conservation of energy to find it as :
.......(1)
We need to find the speed of the rock when it is at height h/4. Let v' is the speed. Using 3rd equation of motion as :
here a = -g and s = h/4
Using equation (1) :
So, the speed of the rock when it is at height h/4 is . Hence, this is the required solution.
Answer:
3.69 m/s
Explanation:
Forces :
mgsin Θ - mumgcosΘ = ma
g x sinΘ - mu x g x cosΘ = a
9.8 x sin 21 - 0.53 x 9.8 x cos 21 = a
a = -1.337 m/s²
so you have final velocity = 0 m/s
initial velocity = ? m/s
Given d = 5.1 m
By kinematics
vf² = vo² + 2ad
0 = vo² + 2 x -1.337*5.1
vo = 3.69 m/s
Answer:
violet
Explanation:
violet has shortest wavelength
Answer:
T1 = 417.48N
T2 = 361.54N
T3 = 208.74N
Explanation:
Using the sin rule to fine the tension in the strings;
Given
amass = 42.6kg
Weight = 42.6 * 9.8 = 417.48N
The third angle will be 180-(60+30)= 90 degrees
Using the sine rule
W/Sin 90 = T3/sin 30 = T2/sin 60
Get T3;
W/Sin 90 = T3/sin 30
417.48/1 = T3/sin30
T3 = 417.48sin30
T3 = 417.48(0.5)
T3 = 208.74N
Also;
W/sin90 = T2/sin 60
417.48/1 = T2/sin60
T2 = 417.48sin60
T2 = 417.48(0.8660)
T2 = 361.54N
The Tension T1 = Weight of the object = 417.48N
